Roof installation having cellular base sheets



Oct. 25, 1966 A. A. DUNLAP, JR

ROOF INSTALLATION HAVING CELLULAR BASE SHEET Filed June 27, 1963 IN V EN TOR. 9

BY ALAN A. DUNLAP, JR.

United States Patent 3,280,528 ROOF INSTALLATION HAVING CELLULAR BASE SHEETS Alan A. Dunlap, 31:, Lancaster Township, Lancaster County, Pa., assignor to Armstrong Cork Company, Lancaster, Pa., a corporation of Pennsylvania Filed June 27, 1963, Ser. No. 291,064 7 Claims. (Cl. 52309) This invention relates generally to roof installations. More particularly the invention relates to roof installations adapted to maintain the roof in a sealed condition despite the expansion and contraction of structural members which open and close the joints.

As set forth in copending patent application Serial No. 244,616, there has always been a problem in keeping a roof sealed throughout the wide variety of Weather conditions normally found in the middle latitudes. Structural members expand and contract as the temperature changes and as moisture is picked up. These changes can open and close the joints between structural members by as much as /2 inch, while inch changes are quite common. Under such conditions, it is extremely difiicult to construct a roof installation which will remain sealed over an extended period of time in the region of the joints and elsewhere on the roof, particularly under traflic conditions. There is, therefore, a need for a roofing installation which will last for many years under varying conditions of service and usage despite the opening and closing of joints and cracks in response to environmental condi tions.

It is the primary object of the present invention to supply such an installation. It is a further object to supply a roofing installation which may be quickly and easily installed on a roof and yet which will withstand the rigorous structural changes and weather changes to which such installations are frequently subjected.

These objects have been accomplished in a surprisingly effective and straightforward manner. The invention comprises in combination a flexible cellular rubber base sheet adhesively secured to the roof. Overlaying the base sheet is a top, Weather-resistant coating, the coating also being resistant if desired to traflic conditions. The flexible cellular rubber base sheet is a closed-cell sheet having a thickness in the range of /8% inch, a density in the range of 69 pounds per cubic foot (preferably 7), and an elongation at the breaking point of at least 150% (preferably 200% The flexible closed-cell rubber base sheet has the advantage of supplying a highly elastic slip plane to take up roof movement. Such a sheet may be prepared in known manner, for example as suggested in US. 2,849,028 and US. 2,873,259. These flexible closed-cell rubber sheets may, however, be made by a variety of processes so long as the resulting sheet possesses the requisite elongation at break, the requisite density, and the requisite thickness. Base sheets thinner than the stated minimum are insufliciently strong to withstand the rigors of roof movement, it being recalled that the base sheet is filled with sufficient closed cells which are really tiny sealed voids throughout the sheet to give the sheet a density in the stated range. At the same time the sheet must have at least the minimum elongation stated in order that it may stretch with the roof movement without breaking.

The base sheet may be manufactured in any convenient width, limited only by the Width of the mills, ovens, and other processing machinery. This means that the base sheet is applied to the roof installation with great convenience since wide sheets ranging up to six feet and more in width may be used in large open areas of the roof, and narrower sheets may be used at peaks, gables, flashings,

3,28,528 Patented Oct. 25, 1966 and other breaks in the flat roof surface. The cellular base sheet is adhered to the subroof structure by means of any convenient adhesives such as a neoprene contact adhesive. Any of the commercially available neoprene latex adhesives may be used, or other material which will hold the base sheet firmly in place and will not destroy it by chemical or solvent action.

Once the base sheet is adhesively secured to the subroof members, the building is protected by What amounts to a weathertight membrane. Adjacent strips of the membrane may be butt jointed, or the edges may be overlapped, normally 1-6 inches, to ensure a seal along the seams.

The top, Weather-resistant coating overlaying the cellular base sheet may be any of the top coatings known in the art. These top coatings may preferably comprise successive layers of neoprene or chlorosulfonated polyethylene rubber, each applied in solvent solution. Alternatively, the top, weather-resistant coating may be applied fr-om a resin or rubber latex in a suflicient number of coatings to yield a Weather-resistant coating having the desired thickness. Hot asphalt may be used, the asphalt being covered with gravel or With other materials to further protect the installation from pedestrian and other traflic. Alternatively, the cellular flexible base sheet may itself carry a flexible rubber top laminate adhesively secured to the base sheet so that the entire roof installation may simply be rolled into place and adhesively secured to the subroof installation. Under such circumstances, the seams may conveniently be sealed by allowing the top coating to protrude beyond the edge of the base sheet for a distance of 1-6 inches, or other convenient distance. The opposing edge against which such edge abuts may then have the top coating displaced an equal amount in order that the exact seam between the top coatings be displaced from the exact seam between the cellular base sheets. Sealing may be accomplished by means of solvent Welding or heating as convenient. Adhesive may be used on the overlapped areas.

One of the outstanding advantages of the roofing installation of the present invention is its ability to cover and hide surface imperfections. Carefully made butt joints will be almost invisible, hence the roof can, if desired, present a monolithic appearance despite the simplicity of its installation. Another advantage of the present roof installation is its unique sound absorbing ability; transmission of the drumming of rain and hail is minimized.

The invention may be better understood by reference to the attached drawings in which FIG. 1 illustrates a piece of the flexible closed-cell base sheet,

FIG. 2 illustrates adjoining base sheets having top, weather-resistant coatings thereon, and

FIG. 3 illustrates a roof installation of the present invention. Like elements have the same number in the drawings.

In FIG. 1, the rubber base sheet 1 has distributed therethrough a multitude of closed cells 2. The face of the sheet 1 may possess a surface skin or it may simply be that which results on slitting a thin sheet from a thicker sheet.

In FIG. 2, the base sheet 1 is adhesively secured at the adhesive line 3 to the top, weather-resistant coating 4. In the region of overlap 5, the top coat 4 of the righthand side of the base sheet, to the right of the base sheet joint 6, carries an extension of the top coating 4, while the left-hand side of the base sheet 1, to the left of the joint 6, carries a displaced top coating 4 in order that the top coating joint 7 may be displaced from the base sheet joint 6.

In FIG. 3, the base sheet 1 is adhesively secured at 8 to the structural members 9 of the roof. The top coating 4 may be an elastomer, an asphalt, or other suitable weatherresistant coating.

I claim:

1. A roof installation adapted to maintain the roof in a sealed condition in spite of the opening and closing of joints and cracks during the normal movement of roof supports, the installation consisting of a roof having subroof structural support members, a flexible preformed cellular rubber base sheet adhesively secured to the top of the support members and spanning the joints and cracks thereof, said cellular base sheet having closed cells throughout its dimensions, and a top, weather-resistant coating substantially covering and overlaying the cellular base sheet, said base sheet being capable of forming a highly elastic slip plane between said subroof support members and said weather resistant coating and having a thickness of Mia- A inch, an elongation at the breaking point of at least 150%, a density in the range of 6-9 pounds per cubic foot, and an elasticity capable of maintaining the sheet elastically responsive during the normal loading and movement of the structural support members.

2. A roof installation according to claim 1 in which said top, weather-resistant coating comprises a chlorosulfonated polyethylene rubber.

3. A roof installation according to claim 1 wherein said top, weather-resistant coating comprises a neoprene coating.

4. A roof installation according to claim 1 in which the joint between adjacent sbase sheets is displaced from References Cited by the Examiner UNITED STATES PATENTS 1,319,879 10/1919 Lindley 94-3 1,447,290 3/1923 Fischer 52-540 2,861,525 11/1958 Curtis et a1. 52515 X 2,873,259 2/1959 Clark 2602.5 3,029,172 4/ 1962 Glass 52-309 X 3,094,447 6/1963 Chamberlain 52309 X 3,111,787 11/1963 Chamberlain 52--173 FOREIGN PATENTS 875,891 8/1961 Great Britain.

OTHER REFERENCES American Roofer and Building Improvement Contrac tor, February 1963, pp. 16 and 17.

Engineering News-Record, p. 103, May 28, 1953.

Journal of American Concrete Institute, p. 5 of News Letter, February 1959.

EARL J. WITMER, Primary Examiner. 

1. A ROOF INSTALLATION ADAPTED TO MAINTAIN THE ROOF IN A SEALED CONDITION IN SPITE OF THE OPENING AND CLOSING OF JOINTS AND CRACKS DURING THE NORMAL MOVEMENT OF ROOF SUPPORTS, THE INSTALLATION CONSISTING OF A ROOF HAVING SUBROOF STRUCTURAL SUPPORT MEMBERS, A FLEXIBLE PERFORMED CELLULAR RUBBER BASE SHEET ADHESIVELY SECURED TO THE TOP OF THE SUPPORT MEMBERS AND SPANNING THE JOINTS AND CRACKS THEREOF, SAID CELLULAR BASE SHEET HAVING CLOSED CELLS THROUGHOUT ITS DIMENSIONS, AND A TOP, WEATHER-RESISTANT COATING SUBSTANTIALLY COVERING AND OVERLAYING THE CELLULAR BASE SHEET, SAID BASE SHEET BEING CAPABLE OF FORMING A HIGHLY ELASTIC SLIP PLANE BETWEEN SAID SUBROOF SUPPORT MEMBERS AND SAID WEATHER RESISTANT COATING AND HAVING A THICKNESS OF 1/8-1/4 INCH, AN ELONGATION AT THE BREAKING POINT OF AT LEAST 150%, A DENSITY IN THE RANGE OF 6-9 POUNDS PER CUBIC FOOT, AND AN ELASTICITY CAPABLE OF MAINTAINING THE SHEET ELASTICALLY RESPONSIVE DURING THE NORMAL LOADING AND MOVEMENT OF THE STRUCTURAL SUPPORT MEMBERS. 